Temporary fix for user-friendly error feedback

Currently, transmart-ui buries any end-user relevant error messages
underneath a layer of technical information. This feature forwards
several of these errors through the plot output. This feature was
already present, and has now been extendend. Should be replaced by
better error handling as discussed in ticket HYVE-12.
:fish:

Whitespace and other code formatting cleanup
Merge branch 'master' into issues/138-kmeans-empty-data-exception-handling
Merge pull request #51 from thehyve/issues/138-kmeans-empty-data-exception-handling

Issues/138 kmeans empty data exception handling